<div class="refentry" lang="en" xml:lang="en"><a id="glPolygonMode"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>glPolygonMode — select a polygon rasterization mode</p></div><div class="refsynopsisdiv"><h2>C Specification</h2><div class="funcsynopsis"><table><tr><td><code class="funcdef">void <b class="fsfunc">glPolygonMode</b>(</code></td><td>GLenum  </td><td><var class="pdparam">face</var>, </td></tr><tr><td> </td><td>GLenum  </td><td><var class="pdparam">mode</var><code>)</code>;</td></tr></table></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="parameters"></a><h2>Parameters</h2><div class="variablelist"><dl><dt><span class="term"><em class="parameter"><code>face</code></em></span></dt><dd><p>
                    Specifies the polygons that <em class="parameter"><code>mode</code></em> applies to.
                    Must be
                    <code class="constant">GL_FRONT</code> for front-facing polygons,
                    <code class="constant">GL_BACK</code> for back-facing polygons,
                    or <code class="constant">GL_FRONT_AND_BACK</code> for front- and back-facing polygons.
                </p></dd><dt><span class="term"><em class="parameter"><code>mode</code></em></span></dt><dd><p>
                    Specifies how polygons will be rasterized.
                    Accepted values are
                    <code class="constant">GL_POINT</code>,
                    <code class="constant">GL_LINE</code>, and
                    <code class="constant">GL_FILL</code>.
                    The initial value is <code class="constant">GL_FILL</code> for both front- and back-facing polygons.
                </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="description"></a><h2>Description</h2><p>
            <code class="function">glPolygonMode</code> controls the interpretation of polygons for rasterization.
            <em class="parameter"><code>face</code></em> describes which polygons <em class="parameter"><code>mode</code></em> applies to:
            front-facing polygons (<code class="constant">GL_FRONT</code>),
            back-facing polygons (<code class="constant">GL_BACK</code>),
            or both (<code class="constant">GL_FRONT_AND_BACK</code>).
            The polygon mode affects only the final rasterization of polygons.
            In particular,
            a polygon's vertices are lit and
            the polygon is clipped and possibly culled before these modes are applied.
        </p><p>
            Three modes are defined and can be specified in <em class="parameter"><code>mode</code></em>:
        </p><div class="variablelist"><dl><dt><span class="term"><code class="constant">GL_POINT</code></span></dt><dd><p>
                        Polygon vertices that are marked as the start of a boundary edge
                        are drawn as points.
                        Point attributes such as
                        <code class="constant">GL_POINT_SIZE</code> and
                        <code class="constant">GL_POINT_SMOOTH</code> control
                        the rasterization of the points.
                        Polygon rasterization attributes other than <code class="constant">GL_POLYGON_MODE</code> have no effect.
                    </p></dd><dt><span class="term"><code class="constant">GL_LINE</code></span></dt><dd><p>
                        Boundary edges of the polygon are drawn as line segments.
                        They are treated as connected line segments for line stippling;
                        the line stipple counter and pattern are not reset between segments
                        (see <a class="citerefentry" href="glLineStipple"><span class="citerefentry"><span class="refentrytitle">glLineStipple</span></span></a>).
                        Line attributes such as
                        <code class="constant">GL_LINE_WIDTH</code> and
                        <code class="constant">GL_LINE_SMOOTH</code> control
                        the rasterization of the lines.
                        Polygon rasterization attributes other than <code class="constant">GL_POLYGON_MODE</code> have no effect.
                    </p></dd><dt><span class="term"><code class="constant">GL_FILL</code></span></dt><dd><p>
                        The interior of the polygon is filled.
                        Polygon attributes such as
                        <code class="constant">GL_POLYGON_STIPPLE</code> and
                        <code class="constant">GL_POLYGON_SMOOTH</code> control the rasterization of the polygon.
                    </p></dd></dl></div></div><div class="refsect1" lang="en" xml:lang="en"><a id="examples"></a><h2>Examples</h2><p>
            To draw a surface with filled back-facing polygons
            and outlined front-facing polygons,
            call
            </p><pre class="programlisting">
glPolygonMode(<code class="constant">GL_FRONT</code>, <code class="constant">GL_LINE</code>);
            </pre><p>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="notes"></a><h2>Notes</h2><p>
            Vertices are marked as boundary or nonboundary with an edge flag.
            Edge flags are generated internally by the GL when it decomposes
            polygons; they can be set explicitly using <a class="citerefentry" href="glEdgeFlag"><span class="citerefentry"><span class="refentrytitle">glEdgeFlag</span></span></a>.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="errors"></a><h2>Errors</h2><p>
            <code class="constant">GL_INVALID_ENUM</code> is generated if either <em class="parameter"><code>face</code></em> or <em class="parameter"><code>mode</code></em> is not
            an accepted value.
        </p><p>
            <code class="constant">GL_INVALID_OPERATION</code> is generated if <code class="function">glPolygonMode</code>
            is executed between the execution of <a class="citerefentry" href="glBegin"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>
            and the corresponding execution of <a class="citerefentry" href="glEnd"><span class="citerefentry"><span class="refentrytitle">glEnd</span></span></a>.
        </p></div><div class="refsect1" lang="en" xml:lang="en"><a id="associatedgets"></a><h2>Associated Gets</h2><p>
            <a class="citerefentry" href="glGet"><span class="citerefentry"><span class="refentrytitle">glGet</span></span></a> with argument <code class="constant">GL_POLYGON_MODE</code>
        </p></div>
        {$pipelinestall}{$examples}
        <div class="refsect1" lang="en" xml:lang="en"><a id="seealso"></a><h2>See Also</h2><p>
            <a class="citerefentry" href="glBegin"><span class="citerefentry"><span class="refentrytitle">glBegin</span></span></a>,
            <a class="citerefentry" href="glEdgeFlag"><span class="citerefentry"><span class="refentrytitle">glEdgeFlag</span></span></a>,
            <a class="citerefentry" href="glLineStipple"><span class="citerefentry"><span class="refentrytitle">glLineStipple</span></span></a>,
            <a class="citerefentry" href="glLineWidth"><span class="citerefentry"><span class="refentrytitle">glLineWidth</span></span></a>,
            <a class="citerefentry" href="glPointSize"><span class="citerefentry"><span class="refentrytitle">glPointSize</span></span></a>,
            <a class="citerefentry" href="glPolygonStipple"><span class="citerefentry"><span class="refentrytitle">glPolygonStipple</span></span></a>
        </p></div><div class="refsect1" lang="en" xml:lang="en"><div id="Copyright"><h2>Copyright</h2><p>
            Copyright © 1991-2006
            Silicon Graphics, Inc. This document is licensed under the SGI
            Free Software B License. For details, see
            <a class="ulink" href="https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/" target="_top">https://web.archive.org/web/20171022161616/http://oss.sgi.com/projects/FreeB/</a>.
        </p></div></div></div>
